A general data storage device mainly includes a control unit, a voltage pull-down module, a volatile memory and a non-volatile memory. The control unit is electrically coupled to a host (such as a computer or a handheld mobile device) and configured to communicate and transmit data with the host. In the operation of the conventional data storage device, the control unit receives and processes commands from the host, writes the target data into the non-volatile memory, or reads the target data from the non-volatile memory. If the data transmitted from the host has a relatively small data amount (e.g., smaller than one page), the control unit may first store the received data into the volatile memory or data buffers and then move the data to the non-volatile memory from the volatile memory or the data buffers when the data is accumulated to a certain amount (e.g., equal to or larger than one page). Besides the data transmitted between the control unit and the host, the control unit also stores the data required for its operation, such as the address mapping table, into the volatile memory.
In general, the voltage pull-down module is configured to convert external power provided by the host into a plurality of low voltages with different voltage levels. The low voltages are then provided to the control unit, the volatile memory and the non-volatile memory as the respective operating voltages. However, the data storage device may have a power drop/loss event in operation. In order to avoid improper operation of the data storage device due to a power drop/loss event, some manufacturers add a charge storage device (or capacitor) into the data storage device as a small spare power supply. Therefore, when a power drop/loss event occurs, the charge storage device can briefly provide power to enable the data storage device to successfully complete the specified task.
However, in general, the charge storage device has a problem in lifetime. That is, when the lifetime of the charge storage device expires or the charge storage device is out of order, the charge storage device will not have expected function unless the user replaces the charge storage device or performs troubleshooting. However, currently there is no appropriate processing mechanism to handle the event such as the lifetime of the charge storage device has expired or the charge storage device is damaged.
In addition, the data storage device also requires a protection mechanism to protect data stored in volatile memory, such as dynamic random access memory (DRAM) or data buffers, when a power drop/loss event occurs.